The present invention relates to the preparation of a gaseous mixture containing a desired molar ratio of hydrogen and carbon monoxide from a feed containing these components in a different molar ratio. It has particular, but not exclusive, application to the provision of synthesis gas containing hydrogen and carbon monoxide in a molar ratio of, for example 1:1.
Synthesis gas (syngas) is a gaseous mixture consisting essentially of hydrogen and carbon monoxide, which, depending upon the level of purity, can contain small amounts of argon, nitrogen, methane and other trace hydrocarbon impurities. Usually, it is obtained by catalytic conversion or partial oxidation of coal, coke, natural gas, or other hydrocarbon feeds. The primary uses of syngas are in the synthesis of methanol (requiring a hydrogen:carbon monoxide (H2:CO) molar ratio of 2:1) and in reactions to produce oxo-alcohols (requiring a H2:CO molar ratio of at least 1:1).
For many of these applications, it is necessary to control the relative proportions of hydrogen and carbon monoxide. Typically, this is achieved by cryogenically separating crude syngas into hydrogen-rich and carbon monoxide-rich product streams and then combining them in the appropriate ratio to produce the required syngas composition. The level of impurities, especially methane and other hydrocarbons, in the crude syngas usually also is reduced during the cryogenic separation.
Industry wants to efficiently produce a purified syngas having a desired H2:CO molar ratio at high pressure from a cryogenic separation without additional compression.
Industry wants to reduce power requirements for compressing syngas product streams.
Industry wants to reduce the amount and/or size of capital equipment and associated costs for syngas production.
Industry wants to efficiently produce syngas having a desired H2:CO molar ratio along with a hydrogen product gas and/or a carbon monoxide product gas.
Related disclosures include: U.S. Pat. Nos. 4,217,759, 4,488,890, 4,525,187, 4,566,886, 5,351,491, 5,609,040, 5,832,747, and 6,161,397, incorporated herein by reference in their entirety.